I just started usinig MSN 8 and it works pretty well. It's got a great junk mail filter. Here's a link to read about it:
http://join.msn.com/?page=features/emailmgmt&pgmarket=en-us&RU=http%3a%2f%2fjoin.msn.com%2f%3fpage%3dmisc%2fspecialoffers%26pgmarket%3den-us